1. Field of the Invention
The present invention relates to a two component dentifrice composition, having a first component containing an alkali metal bicarbonate salt and a second component containing an acid and more particularly to such a composition which exhibits a novel tingling mouth effect and enhanced removal of plaque growth.
2. The Prior Art
The addition of alkali metal bicarbonates to toothpaste for medicinal, general cleansing, or aesthetic purposes is known in the art. These bicarbonates are used as abrasives or polishing agents in dentifrice compositions providing moderate abrasion to remove debris and stained pellicle from tooth surfaces which are accessible to the toothbrush bristles. Further, it is known that bicarbonate-acid mixtures in toothpaste formulations will create an effervescent effect and that that effervescent effect can provide certain mouth feel and moderate cleaning benefits.
British Patent 1 209 319 discloses a bicarbonate containing foaming toothpaste, based on a single composition of an alcohol-containing gel, thickened to a paste with colloidal silica and an acid salt to initiate an acid reaction. The CO.sub.2 released from the acid reaction enhances the cosmetically desirable froth formation of the active detergent conventionally present in toothpaste. However, the disclosed formulation is primarily non-aqueous, having a water content of not more than 10% by weight. For such a non-aqueous dentifrice to generate any appreciable effervescence, the stabilized ingredients will have to go into solution, a relatively slow process when the neat toothpaste is first applied to the teeth. Further, the non-aqueous formulation is composed of from 20 to 50% by weight of ethanol and/or propanol, having significant taste, mouth feel and potential irritation negatives.
U.S. Pat. No. 4,487,757 discloses a dual component alkali metal bicarbonate and acid containing toothpaste, wherein the bicarbonate containing component is isolated from the acid containing component in separate sections of a multisection storage dispenser, to avoid any chemical reaction between the bicarbonate and acid during storage. Upon dispensing the two components first contact each other and are further brought into intimate contact upon use, fostering the acid-base reaction between the bicarbonate and the acid. U.S. Pat. No. 4,487,757 discloses an effervescence which helps clean the teeth; a clean mouth or a clean "mouth feel effect"; and an initial taste which may be somewhat acidic and also salty and becomes subsequently sweeter when the acid is combined with the bicarbonate containing component, in use, in the mouth.
U.S. Pat. No. 5,474,761 discloses oral compositions effective against plaque and gingivitis, containing a nonionic water insoluble antibacterial agent, in which an essential component is bicarbonate salt. The bicarbonate is usually used at a level of from 1 to about 50 percent. Further, the pH of the disclosed oral compositions and/or the pH of such compositions in the mouth is disclosed as being safe for the mouth's hard and soft tissues, from about 8.5 to about 9.5. As will hereinafter be shown, such high pH, bicarbonate containing dentifrices will not yield any appreciable acid-base reaction and hence, will not yield any appreciable effervescence nor the desired associated attributes therewith.
U.S. Pat. No. 5,215,740 discloses a one component dentifrice composition comprising sodium bicarbonate, one or more alkali metal pyrophosphate salts, a soluble fluoride ion source and other adjuvants, in admixture with a buffering agent. The buffering agent is incorporated in the dentifrice sufficient to buffer the pH to about 8.2 to 8.9, so as to decrease the risk of irritation of the oral mucosa or desquamation, as compared with dentifrices excluding such a buffering agent. However as will hereinafter be shown, such an alkaline pH, will inhibit any significant base/acid reaction with the bicarbonate and minimize any effervescence and associated product attributes.
There is an ongoing need for new and novel mouth feel benefits to promote the use of toothpaste, especially by children, as well as, for enhanced cleaning of the oral surfaces to better remove plaque growth and hence, reduce the oral decay and disease associated with plaque.